That's how ZocDoc was born, CEO Cyrus Massoumi told CNBC's "Squawk on the Street"Friday. ZocDoc is a free service that allows people to use the Internet to find a doctor and get an immediate appointment.

"I had to find a doctor. I went to the insurance company website and it took me four days to get an appointment," he said. "I thought, there has to be a better way to give people access to health care."

People make reservations online and buy groceries online, so why not medical appointments, he said.

The company, which has more than 1.2 million users a month, started during the 2008 financial crisis, a time "when people thought startups would never be able to raise capital again," he said. ZocDoc's first market was New York, and last week the company opened its 17th market, in Detroit. There will be more, the CEO said.

The company has raised $75 million as part of its plans to go nationwide next year, he said, and that will be ZocDoc's focus rather than going public.

"When you have a [business] model that works, you want to do it as quickly as possible," he said of trying to expand rapidly. Part of the problem is there are "so many entrepreneurs" ready to copy ideas like ZocDoc, and "sophisticated investors" ready to fund them, he added.